Field of the Invention
The inventions disclosed and taught herein relate generally to compositions and processes for use in downhole, subterranean operations, and more specifically are related to earth metal peroxide compositions for use in downhole hydrocarbon recovery operations.
Description of the Related Art
Fluids of various types are used in well working operations. One major use of fluids is in hydraulic fracturing, which is used to enhance the productivity of a well. Fracturing fluids typically have a high viscosity to generate a desired fracture geometry and to carry proppant into a formation. Water-based fracturing fluids usually utilize an additive which imparts sufficient viscosity to the fluid to maintain the proppant in suspension. Representative viscosifying additives include hydrophilic polysaccharide polymers such as guar gum, hydroxypropyl guar, or carboxymethyl hydroxypropyl guar. The hydrophilic polymer may also be crosslinked. Crosslinking increases the effective molecular weight of the polymer creating an enhanced viscosity of the aqueous fluid. Once the formation is fractured and the proppant placed, it is desirable to reduce the viscosity of the fluid so that it may be easily removed, thereby preventing damage to the formation and fracture permeability. Conventionally, this breaking of the aqueous gelled fluid is accomplished by continuously adding a viscosity breaker to the fluid during the fracturing operation.
Fracturing fluid breaker technology using dry powdered alkaline earth metal peroxides, such as magnesium peroxide and calcium peroxide is well known, but has several limitations. The fine particle sizes of magnesium peroxide (MgO2) (D-10/1.2 microns, D-50/4.5 microns, D-90/257.2 microns) and calcium peroxide (CaO2) (D-10/1.0 microns, D-50/4.3 microns, D-90/11.0 microns) is problematic during a continuous mix pumping operation. Poor dispersion of fine dry particles in the fracturing mixture, or loss of material due to windy atmospheric conditions can alter the required breaker concentration resulting in insufficient or erratic viscosity reduction, and significant damage to the permeability of the formation or the proppant pack placed by the fracturing fluid.
The inventions disclosed and taught herein are directed to improved compositions, systems, and methods for preparation and use of formation treating fluids for use in hydrocarbon recovery operations, wherein the compositions comprise one or more earth metal peroxides.